A ROOF FALL OCCURRED IN THE NO2 LW E2 PANEL DURING THE SHEILD RECOVERY PROCESS. THE ROOF FALL WAS 29'LX5'WX15'H. THE ROOF FALL EXTENDED FROM THE NO.166 SHIELD IN THE N0172 SHIELD AND WENT FROM THE SHIELD TIPS TO THE FACELINE. THIS AREA HAD PREVIOUSLY BEEN SUPPORTED WITH CABLE BOLTS IBEAMS AND WOOD PLANKING. NO PERSONS WERE INJUREDOR PROPERTY DAMAGE OCCURED BUT 8 SHIELDS WERE LE